Lubricating oil compositions with improved friction properties

ABSTRACT

The present invention concerns friction reducers for use in lubricating oil compositions which comprise certain groups of aromatic compounds, esters, narrow mixtures of base stocks, and/or amorphous polymers such as amorphous olefin copolymers. These compositions can provide substantial reductions in the coefficient of friction and fuel economy improving benefits when admixed to lubricating oils without deleterious effects such as instability, undesirable high viscosities and deposits. In one aspect of the invention, pentaerythritol esters and optionally triol esters are added to lubricating oil compositions to provide reduced friction and improved fuel economy. In a second aspect of the invention, similar results are obtained by adding hydrocarbyl aromatics to a lubricating oil composition containing one or more of Groups II and III base stock. In a third aspect, the invention concerns a lubricating oil composition comprising an amorphous olefin copolymer and one or more of Groups II and III base stocks. In one embodiment, the third aspect also includes one or more of hydrocarbyl aromatics and polyol esters as part of the composition. In a forth aspect, moderate concentrations of hydrocarbyl aromatics are used in a lubricating oil composition comprising paraffinic base oil stocks and preferably a borated polyisobutenyl succinimide ashless dispersant.

CROSS-REFERENCE TO RELATED APPLICATION(S):

[0001] Non-Provisional Application based on Provisional Application No.60/353,738 filed Jan. 31, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to lubricating oil compositions suitablefor use in internal combustion engines.

[0004] 2. Background

[0005] Lubricating oils for internal combustion engines contain inaddition to at least one base lubricating oil, additives which enhancethe performance of the lubricating oil. A variety of additives such asdetergents, dispersants, friction reducers, viscosity index improvers,antioxidants, corrosion inhibitors, antiwear additives, pour pointdepressants, seal compatibility additives, and antifoam agents are usedin lubricating oil compositions.

[0006] It is critical to maintain sufficiently high lubricating filmthickness on metal surfaces in order to maintain low friction and reducewear of metal parts at a variety of operating temperatures. It is alsoimportant to maintain cleanliness over the entire range of operatingconditions while reducing wear to a minimum and to maintain a goodoverall lubricant performance under the most severe operatingconditions. Conventional lubricant and engine oil technology reliesheavily on traditional friction reducers which can be chosen from one ormore classes of friction reducing compounds exemplified by alcohols,hydrocarbyl diols, hydrocarbyl triols, alkane diols or triols, esters,fatty esters, hydroxy esters, fatty acid amides such as oleamide,hydroxy alkyl hydrocarbyl amides, bis hydroxyalkyl hydrocarbyl amidessuch as bis(2-hydroxyethyl)oleamide, hydroxy alkyl hydrocarbyl amines,bis hydroxyalkyl hydrocarbyl amines such asbis(2-hydroxyethyl)oleylamine, borated counterparts of the above,acylated counterparts of the above, phosphorus based compositions suchas trioleyl phosphites, molybdenum compounds such as inorganicmolybdenum and/or organic molybdenum compounds including molybdenumdithiocarbamates, molybdenum phosphorodithioates, molybdenum complexesof amines and/or alcoholic moieties. Friction reducers often includemixtures of two or more of the above classes of components. Several ofthe above prior art friction reducing compositions are found to havesignificant and often undesirable side-effects. It is thus desirable tohave several improved fuel economy components and/or systems to be ableto choose from in the formulation of high quality fuel economy improvinglubricants.

SUMMARY OF THE INVENTION

[0007] The present invention concerns friction reducers for use inlubricating oil compositions which comprise certain groups of aromaticcompounds, esters, narrow mixtures of base stocks, and/or amorphouspolymers such as amorphous olefin copolymers. These compositions canprovide substantial reductions in the coefficient of friction and fueleconomy improving benefits when admixed to lubricating oils withoutdeleterious effects such as instability, undesirable high viscositiesand deposits.

[0008] In one aspect of the invention, pentaerythritol esters andoptionally triol esters are added to lubricating oil compositions toprovide reduced friction and improved fuel economy. In a second aspectof the invention, similar results are obtained by adding hydrocarbylaromatics to a lubricating oil composition containing one or more ofGroup II base stock, Group III base stock, and wax isomerate base stock.In a third aspect, the invention concerns a lubricating oil compositioncomprising an amorphous olefin copolymer and one or more of Group IIbase stock, Group III base stock, and wax isomerate base stock. In oneembodiment, the third aspect also includes one or more of hydrocarbylaromatics and polyol esters as part of the composition. In a forthaspect, moderate concentrations of hydrocarbyl aromatics are used in alubricating oil composition comprising paraffinic base oil stocks andpreferably a borated polyisobutenyl succinimide ashless dispersant.

BRIEF DESCRIPTION OF THE DRAWING

[0009]FIG. 1 is a plot of coefficient of friction as a function oftemperature for various compositions.

DETAILED DISCRIPTION OF THE INVENTION

[0010] Engine oils contain a base lube oil and a variety of additives.These additives include detergents, dispersants, friction reducers,viscosity index improvers, antioxidants, corrosion inhibitors, antiwearadditives, pour point depressants, seal compatibility additives, andantifoam agents. To be effective, these additives must be oil-soluble oroil-dispersible. By oil-soluble, it is meant that the compound issoluble in the base oil or lubricating oil composition under normalblending conditions.

[0011] The instant invention concerns certain groups of aromaticcompounds, esters, mixtures of base stocks, and/or amorphous polymerssuch as amorphous olefin copolymers that can provide substantialreductions in the coefficient of friction and fuel economy improvingbenefits when admixed to lubricating oils without deleterious effectssuch as instability, undesirable high viscosities and deposits.

[0012] In one aspect, the present invention concerns certainpentaerythritol esters which are found to provide unexpected andsignificant fuel economy improving (friction reducing) benefits whenformulated into lubricants containing hydrocarbyl aromatic compositions.This fuel economy improvement enhancement can be further improved withthe addition of certain esters to the above-mentioned pentaerythritolesters. In particular, this additional fuel economy improvement is seenwith a mixed triol ester and pentaerythritol ester system in thepresence of a relatively low concentration of hydrocarbyl aromatics suchas alkylated naphthalene. Useful concentrations of hydrocarbyl aromaticsrange from about 1% or more. We believe that about 2% to about 45% ofsuch hydrocarbyl aromatics is often preferred, more preferably about 2%to about 30%, even more preferably about 3% to about 15%.

[0013] Desirable esters include pentaerythritol esters, derived frommono-, di-, and poly pentaerythritol polyols reacted with mixedhydrocarbyl acids (RCO₂H), and where a substantial amount of theavailable —OH groups are converted to esters. The substituenthydrocarbyl groups, R, of the acid moiety and ester comprise from aboutC₆ to about C₁₆ or more, with preferable ranges being about C₆ to aboutC₁₄, and may comprise alkyl, alkenyl, cycloalkyl, cycloalkenyl, linear,branched, and related hydrocarbyl groups, and can optionally contain S,N, and/or O groups. Pentaerythritol esters with mixtures of substituenthydrocarbyl groups, R, are often preferred. For example, substituenthydrocarbyl groups, R, may comprise a substantial amount of C₈ and C₁₀hydrocarbyl moieties in the proportions of about 1:4 to 4:1. In a mode,a preferred pentaerythritol ester has R groups comprising approximatelyabout 55% C₈, about 40% C₁₀, and the remainder approximately 5% C₆ andC₁₂₊ moieties. For example, one useful pentaerythritol ester has aviscosity index of about 148, a pour point of about 3° C. and akinematic viscosity of about 5.9 cSt at 100° C. The pentaerythritolesters can be used in lubricant compositions at concentrations of about3% to about 30%, preferably about 4% to about 20%, and more preferablyabout 5% to about 15%.

[0014] Esters may also include esters of trimethylolpropane andtrimethylolethane and the like.

[0015] The hydrocarbyl aromatics that can be used can be any hydrocarbylmolecule that contains at least about 5% of its weight derived from anaromatic moiety such as a benzenoid moiety or naphthenoid moiety, ortheir derivatives. These hydrocarbyl aromatics include alkyl benzenes,alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyldiphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol, andthe like. The aromatic can be mono-alkylated, dialkylated,polyalkylated, and the like. The aromatic can be mono- orpoly-functionalized. The hydrocarbyl groups can also be comprised ofmixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups,cycloalkenyl groups and other related hydrocarbyl groups. Thehydrocarbyl groups can range from about C₆ up to about C₆₀ with a rangeof about C₈ to about C₄₀ often being preferred. A mixture of hydrocarbylgroups is often preferred. The hydrocarbyl group can optionally containsulfur, oxygen, and/or nitrogen containing substituents. The aromaticgroup can also be derived from natural (petroleum) sources, provided atleast about 5% of the molecule is comprised of an above-type aromaticmoiety. Viscosities at 100° C. of approximately 3 cSt to about 50 cStare preferred, with viscosities of approximately 3.4 cSt to about 20 cStoften being more preferred for the hydrocarbyl aromatic component. Inone embodiment, an alkyl naphthalene where the alkyl group is primarilycomprised of 1-hexadecene is used. Other alkylates of aromatics can beadvantageously used. Naphthalene, for example, can be alkylated witholefins such as octene, decene, dodecene, tetradecene or higher,mixtures of similar olefins, and the like. Useful concentrations ofhydrocarbyl aromatic in a lubricant oil composition can be about 2% toabout 25%, preferably about 4% to about 20%, and more preferably about4% to about 15%, depending on the application.

[0016] Alkylated aromatics such as the hydrocarbyl aromatics of thepresent invention may be produced by well-known Friedel-Craftsalkylation of aromatic compounds. See Friedel-Crafts and RelatedReactions, Olah, G. A. (ed), Interscience Publishers, New York, 1963.For example, an aromatic compound, such as benzene or naphthalene, isalkylated by an olefin, alkyl halide or alcohol in the presence of aFriedel-Crafts catalyst. See Friedel-Crafts and Related Reactions, Vol.2, part 1, chapters 14, 17, and 18, See Olah, G. A. (ed), IntersciencePublishers, New York, 1964. Many homogeneous or heterogeneous solidcatalysts are known to one skilled in the art. The choice of catalystdepends on the reactivity of the starting materials and product qualityrequirements. For example, strong acids such as AlCl₃, BF₃, or HF may beused. In some cases, milder catalysts such as FeCl₃ or SnCl₄ arepreferred. Other alkylation technology uses zeolites or solid superacids.

[0017] Fuel economy enhancements are seen with synergistic mixtures of(a) Group II or Group III paraffinic oil blends, including wax isomeratebase oils, and (b) hydrocarbyl aromatics. In particular, the abovementioned base stocks comprising certain hydroprocessed base oils, inthe presence of low concentrations of polyol based esters (such as thosederived from trimethylolpropane and mixed hydrocarbyl acids), andhydrocarbyl aromatics (such as alkylated naphthalene) are found toprovide unexpected and significant fuel economy improving (frictionreducing) benefits when directly compared to lubricants containingrelatively high quantities of about 40% of high quality synthetic fluidsderived from olefin oligomers such as oligomers of 1-decene. For thecomparison, both groups of base stocks have viscosities of about 4 toabout 50 cSt at 100° C. and similar viscosity indices of approximately110 to approximately 150 or greater.

[0018] In another aspect of the invention, certain amorphous olefincopolymers are found to provide unexpected and significant fuel economyimproving (friction reducing) benefits when formulated into lubricants,especially those containing significant amounts of Group II or Group IIIbase oils, including wax isomerates, having viscosity indices of about110 to about 150 or greater. Such olefin copolymers are notpredominantly crystalline. Copolymers used in this invention havemolecular weights in the range of about 20,000 or higher, preferably60,000 or higher, more preferably 100,000 or higher and even morepreferably 150,000 or higher. For example, in one embodiment, amorphousetheylene-propylene copolymers comprising significant to major amountsof propylene-derived copolymers have molecular weights in the range ofabout 20,000 or higher. We believe that the fuel economy benefit can befurther enhanced when the above amorphous olefin copolymer is used inthe presence of a traditional ester and/or hydrocarbyl aromatic such asalkyl naphthalene at concentrations of about 1% to about 30% or more,preferably about 2% to about 25%, or more preferably about 3% to about20% in the finished formulated lubricant.

[0019] In the instant invention, use of these amorphous olefincopolymers gives surprising low-temperature pumpability performance inlubricant compositions.

[0020] In another aspect of the invention, significant fuel economyenhancements are attained with the use of moderate concentrations ofhydrocarbyl aromatics, preferably in the presence of at least a minorconcentration of Group II or Group III hydrocracked and/or hydrotreatedbase stocks, including wax isomerates. These hydrocarbyl aromatics aredescribed above. Group II and Group III base stocks and wax isomeratebase stocks are described below. We also believe that the presence ofcertain ashless dispersants can significantly contribute to the fueleconomy enhancements observed.

[0021] For example, one preferred composition comprising about 20%hydrocarbyl aromatic, about 40% Group II paraffinic base stock, about 3weight percent borated polyisobutyl succinimide ashless dispersant isfound to be particularly useful. Useful ashless dispersants aredescribed below.

[0022] Group II and/or Group III hydroprocessed or hydrocracked basestocks, including wax isomerates, or their synthetic counterparts suchas polyalphaolefin lubricating oils are preferred as lubricating basestocks when used in conjunction with the components of each of theaspects of the present invention. At least about 20% of the totalcomposition should comprise such Group II or Group III base stocks,including wax isomerates, with at least about 30% on occasion being morepreferable, with at least about 50% on occasion being more preferableand more than about 80% on occasion being even more preferable.Gas-to-Liquids base stocks can also be preferentially used with thecomponents of this invention as a portion or all of the base stocks usedto formulate the finished lubricant. A mixture of all or some of suchbase stocks can be used to advantage and can often be preferred. Webelieve that the improvement and benefit is best when the components ofthis invention are added to lubricating systems comprised of primarilyGroup II and or Group III base stocks, including wax isomerates, with upto lesser quantities of alternate fluids such as the above describedhydrocarbyl aromatics as exemplified by C₁₂, C₁₄, C₁₆, and/or C₁₈alkylated naphthalenes. In some instances, hydrocarbyl aromaticsproducts comprising substantially mono-alkylated naphthalene can bepreferred.

[0023] Other components, including effective amounts of co-base stocks,and various performance additives can be advantageously used with thecomponents of this invention. These co-base stocks includepolyalphaolefin oligomeric low- and moderate- and high-viscosity oils,dibasic acid esters, polyol esters, other hydrocarbon oils such as thosederived from gas to liquids type technology, supplementary hydrocarbylaromatics and the like. These co-base stocks can also include somequantity of decene-derived trimers and tetramers, and also some quantityof Group I base stocks, provided that the above Group II and/or GroupIII type base stocks, including wax isomerates, predominate and make upat least about 50% of the total base stocks contained in fluidscomprised of the elements of the above invention requiring a substantialportion of such stocks. The base stocks, co-base stocks and otherperformance additives are discussed in more detail below.

[0024] The instant invention can be used with additional lubricantcomponents in effective amounts in lubricant compositions, such as forexample polar and/or non-polar lubricant base oils, and performanceadditives such as for example, but not limited to, oxidation inhibitors,metallic and non-metallic dispersants, metallic and non-metallicdetergents, corrosion and rust inhibitors, metal deactivators, anti-wearagents (metallic and non-metallic, phosphorus-containing andnon-phosphorus, sulfur-containing and non-sulfur types), extremepressure additives (metallic and non-metallic, phosphorus-containing andnon-phosphorus, sulfur-containing and non-sulfur types), anti-seizureagents, pour point depressants, wax modifiers, viscosity modifiers, sealcompatibility agents, friction modifiers, lubricity agents,anti-staining agents, chromophoric agents, defoamants, demulsifiers, andothers. For a review of many commonly used additives see Klamann inLubricants and Related Products, Verlag Chemie, Deerfield Beach, Fla.;ISBN 0-89573-177-0, which also gives a good discussion of a number ofthe lubricant additives discussed mentioned below. Reference is alsomade “Lubricant Additives” by M. W. Ranney, published by Noyes DataCorporation of Parkridge, N.J. (1973).

[0025] Base Oil

[0026] A wide range of lubricating oils is known in the art. Lubricatingoils that are useful in the present invention are both natural oils andsynthetic oils. Natural and synthetic oils (or mixtures thereof) can beused unrefined, refined, or rerefined (the latter is also known asreclaimed or reprocessed oil). Unrefined oils are those obtaineddirectly from a natural or synthetic source and used without addedpurification. These include shale oil obtained directly from retortingoperations, petroleum oil obtained directly from primary distillation,and ester oil obtained directly from an esterification process. Refinedoils are similar to the oils discussed for unrefined oils except refinedoils are subjected to one or more purification steps to improve the atleast one lubricating oil property. One skilled in the art is familiarwith many purification processes. These processes include solventextraction, secondary distillation, acid extraction, base extraction,filtration, and percolation. Rerefined oils are obtained by processesanalogous to refined oils but using an oil that has been previouslyused.

[0027] Groups I, II, III, IV and V are broad categories of base oilstocks developed and defined by the American Petroleum Institute (APIPublication 1509; www.API.org) to create guidelines for lubricant baseoils. Group I base stock generally have a viscosity index of betweenabout 80 to 120 and contains greater than about 0.03% sulfur and/or lessthan about 90% saturates. Group II base stocks generally have aviscosity index of between about 80 to 120, and contain less than orequal to about 0.03% sulfur and greater than or equal to about 90%saturates. Group III stock generally has a viscosity index greater thanabout 120 and contain less than or equal to about 0.03% sulfur andgreater than about 90% saturates. Group IV includes polyalphaolefins(POA). Group V base stock includes base stocks not included in GroupsI-IV. The table below summarizes properties of each of these fivegroups. Base Oil Properties Saturates Sulfur Viscosity Index Group I <90&/or  >0.03% &  ≧80 & <120 Group II ≧90 & ≦0.03% &  ≧80 & <120 Group III≧90 & ≦0.03% & ≧120 Group IV Defined as polyalphaolefins (PAO) Group VAll other base oil stocks not included in Groups I, II, III, or IV

[0028] Natural oils include animal oils, vegetable oils (castor oil andlard oil, for example), and mineral oils. Animal and vegetable oilspossessing favorable thermal oxidative stability can be used. Of thenatural oils, mineral oils are preferred. Mineral oils vary widely as totheir crude source, for example, as to whether they are paraffinic,naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal orshale are also useful in the present invention. Natural oils vary alsoas to the method used for their production and purification, forexample, their distillation range and whether they are straight run orcracked, hydrorefined, or solvent extracted.

[0029] Synthetic oils include hydrocarbon oil. Hydrocarbon oils includeoils such as polymerized and interpolymerized olefins (polybutylenes,polypropylenes, propylene isobutylene copolymers, ethylene-olefincopolymers, and ethylene-alphaolefin copolymers, for example).Polyalphaolefin (PAO) oil base stocks are a commonly used synthetichydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄olefins or mixtures thereof may be utilized. See U.S. Pat. Nos.4,956,122; 4,827,064; and 4,827,073, which are incorporated herein byreference in their entirety.

[0030] The number average molecular weights of the PAOs, which are knownmaterials and generally available on a major commercial scale fromsuppliers such as ExxonMobil Chemical Company, Chevron-Phillips,BP-Amoco, and others, typically vary from about 250 to about 3,000,although PAO's may be made in viscosities up to about 100 cSt (100° C.).The PAOs are typically comprised of relatively low molecular weighthydrogenated polymers or oligomers of alphaolefins which include, butare not limited to, C₂ to about C₃₂ alphaolefins with the C₈ to aboutC₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like,being preferred. The preferred polyalphaolefins are poly-1-octene,poly-1-decene and poly-1-dodecene and mixtures thereof and mixedolefin-derived polyolefins. However, the dimers of higher olefins in therange of C₁₄ to C₁₈ may be used to provide low viscosity basestocks ofacceptably low volatility. Depending on the viscosity grade and thestarting oligomer, the PAOs may be predominantly trimers and tetramersof the starting olefins, with minor amounts of the higher oligomers,having a viscosity range of 1.5 to 12 cSt.

[0031] The PAO fluids may be conveniently made by the polymerization ofan alphaolefin in the presence of a polymerization catalyst such as theFriedel-Crafts catalysts including, for example, aluminum trichloride,boron trifluoride or complexes of boron trifluoride with water, alcoholssuch as ethanol, propanol or butanol, carboxylic acids or esters such asethyl acetate or ethyl propionate. For example the methods disclosed byU.S. Pat. No. 4,149,178 or U.S. Pat. No. 3,382,291 may be convenientlyused herein. Other descriptions of PAO synthesis are found in thefollowing U.S. Pat. Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930;4,367,352; 4,413,156; 4,434,408; 4,910,355; 4,956,122; and 5,068,487.The dimers of the C₁₄ to C₁₈ olefins are described in U.S. Pat. No.4,218,330. All of the aforementioned patents are incorporated byreference herein in their entirety.

[0032] Other useful synthetic lubricating base stocks oils may also beutilized, for example those described in the seminal work “SyntheticLubricants”, Gunderson and Hart, Reinhold Publ. Corp., New York 1962,which is incorporated in its entirety.

[0033] In alkylated aromatic stocks, the alkyl substituents aretypically alkyl groups of about 8 to 25 carbon atoms, usually from 10 to18 carbon atoms and up to three such substituents may be present, asdescribed for the alkyl benzenes in ACS Petroleum Chemistry Preprint1053-1058, “Poly n-Alkylbenzene Compounds: A Class of Thermally Stableand Wide Liquid Range Fluids”, Eapen et al, Phila. 1984. Tri-alkylbenzenes may be produced by the cyclodimerization of 1-alkynes of 8 to12 carbon atoms as described in U.S. Pat. No. 5,055,626. Otheralkylbenzenes are described in European Patent Application No. 168534and U.S. Pat. No. 4,658,072. Alkylbenzenes are used as lubricantbasestocks, especially for low-temperature applications (arctic vehicleservice and refrigeration oils) and in papermaking oils. They arecommercially available from producers of linear alkylbenzenes (LABs)such as Vista Chem. Co, Huntsman Chemical Co., Chevron Chemical Co., andNippon Oil Co. The linear alkylbenzenes typically have good low pourpoints and low temperature viscosities and VI values greater than 100together with good solvency for additives. Other alkylated aromaticswhich may be used when desirable are described, for example, in“Synthetic Lubricants and High Performance Functional Fluids”, Dressler,H., chap 5, (R. L. Shubkin (Ed.)), Marcel Dekker, N.Y. 1993.

[0034] Other useful lubricant oil base stocks include wax isomerate basestocks and base oils, comprising hydroisomerized waxy stocks (e.g. waxystocks such as gas oils, slack waxes, fuels hydrocracker bottoms, etc.),hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocksand base oils, and other wax isomerate hydroisomerized base stocks andbase oils, or mixtures thereof Fischer-Tropsch waxes, the high boilingpoint residues of Fischer-Tropsch synthesis, are highly paraffinichydrocarbons with very low sulfur content. The hydroprocessing used forthe production of such base stocks may use an amorphoushydrocracking/hydroisomerization catalyst, such as one of thespecialized lube hydrocracking (LHDC) catalysts or a crystallinehydrocracking/hydroisomerization catalyst, preferably a zeoliticcatalyst. For example, one useful catalyst is ZSM-48 as described inU.S. Pat. No. 5,075,269, the disclosure of which is incorporated hereinby reference in its entirety. Processes for makinghydrocracked/hydroisomerized distillates andhydrocracked/hydroisomerized waxes are described, for example, in U.S.Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as inBritish Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Eachof the aforementioned patents is incorporated herein in their entirety.Particularly favorable processes are described in European PatentApplication Nos. 464546 and 464547, also incorporated herein byreference. Processes using Fischer-Tropsch wax feeds are described inU.S. Pat. No. 4,594,172 and 4,943,672, the disclosure of which isincorporated herein by reference in their entirety. Gas-to-Liquids (GTL)base oils, Fischer-Tropsch wax derived base oils, and other wax-derivedhydroisomerized (wax isomerate) base oils be advantageously used in theinstant invention, and may have useful kinematic viscosities at 100° C.of about 3 cSt to about 50 cSt, preferably about 3 cSt to about 30 cSt,more preferably about 3.5 cSt to about 25 cSt, as exemplified by GTL 4with kinematic viscosity of about 4.0 cSt at 100° C. and a viscosityindex of about 141. These Gas-to-Liquids (GTL) base oils,Fischer-Tropsch wax derived base oils, and other wax-derivedhydroisomerized base oils may have useful pour points of about −20° C.or lower, and under some conditions may have advantageous pour points ofabout −25° C. or lower, with useful pour points of about −30° C. toabout −40° C. or lower. Useful compositions of Gas-to-Liquids (GTL) baseoils, Fischer-Tropsch wax derived base oils, and wax-derivedhydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301;6,090,989, and 6,165,949 for example, and are incorporated herein intheir entirety by reference.

[0035] Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived baseoils, have a beneficial kinematic viscosity advantage over conventionalGroup II and Group III base oils, which may be very advantageously usedwith the instant invention. Gas-to-Liquids (GTL) base oils can havesignificantly higher kinematic viscosities, up to about 20-50 cSt at100° C., whereas by comparison commercial Group II base oils can havekinematic viscosities, up to about 15 cSt at 100° C., and commercialGroup III base oils can have kinematic viscosities, up to about 10 cStat 100° C. The higher kinematic viscosity range of Gas-to-Liquids (GTL)base oils, compared to the more limited kinematic viscosity range ofGroup II and Group III base oils, in combination with the instantinvention can provide additional beneficial advantages in formulatinglubricant compositions. Also, the exceptionally low sulfur content ofGas-to-Liquids (GTL) base oils, and other wax-derived hydroisomerizedbase oils, in combination with the low sulfur content of suitable olefinoligomers and/or alkyl aromatics base oils, and in combination with theinstant invention can provide additional advantages in lubricantcompositions where very low overall sulfur content can beneficiallyimpact lubricant performance.

[0036] Alkylene oxide polymers and interpolymers and their derivativescontaining modified terminal hydroxyl groups obtained by, for example,esterification or etherification are useful synthetic lubricating oils.By way of example, these oils may be obtained by polymerization ofethylene oxide or propylene oxide, the alkyl and aryl ethers of thesepolyoxyalkylene polymers (methyl-polyisopropylene glycol ether having anaverage molecular weight of about 1000, diphenyl ether of polyethyleneglycol having a molecular weight of about 500-1000, and the diethylether of polypropylene glycol having a molecular weight of about 1000 to1500, for example) or mono- and polycarboxylic esters thereof (theacidic acid esters, mixed C₃₋₈ fatty acid esters, or the C₁₃Oxo aciddiester of tetraethylene glycol, for example).

[0037] Esters comprise a useful base stock. Additive solvency and sealcompatibility characteristics may be secured by the use of esters suchas the esters of dibasic acids with monoalkanols and the polyol estersof monocarboxylic acids. Esters of the former type include, for example,the esters of dicarboxylic acids such as phthalic acid, succinic acid,alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid,suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc.,with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types ofesters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexylfumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate,dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

[0038] Particularly useful synthetic esters are those which are obtainedby reacting one or more polyhydric alcohols, preferably the hinderedpolyols (such as the neopentyl polyols e.g. neopentyl glycol,trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylolpropane, pentaerythritol and dipentaerythritol) with alkanoic acidscontaining at least about 4 carbon atoms (preferably C₅ to C₃₀ acidssuch as saturated straight chain fatty acids including caprylic acid,capric acid, lauric acid, myristic acid, palmitic acid, stearic acid,arachic acid, and behenic acid, or the corresponding branched chainfatty acids or unsaturated fatty acids such as oleic acid, or mixturesof any of these materials).

[0039] Suitable synthetic ester components include the esters oftrimethylol propane, trimethylol butane, trimethylol ethane,pentaerythritol and/or dipentaerythritol with one or more monocarboxylicacids containing from about 5 to about 10 carbon atoms. These esters arewidely available commercially, for example, the Mobil P-41 and P-51esters ExxonMobil Chemical Company).

[0040] Silicon-based oils are another class of useful syntheticlubricating oils. These oils include polyalkyl-, polyaryl-, polyalkoxy-,and polyaryloxy-siloxane oils and silicate oils. Examples of suitablesilicon-based oils include tetraethyl silicate, tetraisopropyl silicate,tetra-(2-ethylhexyl)silicate, tetra-(4-methyl-hexyl)silicate,tetra-(p-tert-butylphenyl) silicate, hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl) siloxanes, and poly-(methyl-2-mehtylphenyl)siloxanes.

[0041] Another class of synthetic lubricating oil is esters ofphosphorous-containing acids. These include, for example, tricresylphosphate, trioctyl phosphate, diethyl ester of decanephosphonic acid.Another class of oils includes polymeric tetrahydrofurans and the like.

[0042] Besides unique additive effects of hydrocarbyl aromatics and highmolecular weight olefin oligomers of this invention, we believe thathighly refined, low sulfur Group II/III base oils (such ashydroprocessed oils, HDP) and wax isomerate base oil may be used inplace or in addition to Group IV and V base oils as the base stocks usedin combination with the components of this invention to provide theabove-documented superior performance characteristics.

[0043] The types and quantities of performance additives used incombination with the instant invention in lubricant compositions are notlimited by the examples shown herein as illustrations.

[0044] Anitwear and EP Additives

[0045] Internal combustion engine lubricating oils require the presenceof antiwear and/or extreme pressure (EP) additives in order to provideadequate antiwear protection for the engine. Increasingly specificationsfor engine oil performance have exhibited a trend for improved antiwearproperties of the oil. Antiwear and extreme EP additives perform thisrole by reducing friction and wear of metal parts.

[0046] While there are many different types of antiwear additives, forseveral decades the principal antiwear additive for internal combustionengine crankcase oils is a metal alkylthiophosphate and moreparticularly a metal dialkyldithiophosphate in which the primary metalconstituent is zinc, or zinc dialkyldithiophosphate (ZDDP). ZDDPcompounds generally are of the formula Zn[SP(S)(OR¹)(OR²)]₂ where R¹ andR² are C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups. These alkylgroups may be straight chain or branched. The ZDDP is typically used inamounts of from about 0.4 to 1.4 weight percent of the total lube oilcomposition, although more or less can often be used advantageously.

[0047] However, it is found that the phosphorus from these additives hasa deleterious effect on the catalyst in catalytic converters and also onoxygen sensors in automobiles. One way to minimize this effect is toreplace some or all of the ZDDP with phosphorus-free antiwear additives.

[0048] A variety of non-phosphorous additives are also used as antiwearadditives. Sulfurized olefins are useful as antiwear and EP additives.Sulfur-containing olefins can be prepared by sulfurization or variousorganic materials including aliphatic, arylaliphatic or alicyclicolefinic hydrocarbons containing from about 3 to 30 carbon atoms,preferably 3-20 carbon atoms. The olefinic compounds contain at leastone non-aromatic double bond. Such compounds are defined by the formula

R³R⁴C═CR⁵R⁶

[0049] where each of R³-R⁶ are independently hydrogen or a hydrocarbonradical. Preferred hydrocarbon radicals are alkyl or alkenyl radicals.Any two of R³-R⁶ may be connected so as to form a cyclic ring.Additional information concerning sulfurized olefins and theirpreparation can be found in U.S. Pat. No. 4,941,984, incorporated byreference herein in its entirety.

[0050] The use of polysulfides of thiophosphorous acids andthiophosphorous acid esters as lubricant additives is disclosed in U.S.Pat. Nos. 2,443,264; 2,471,115; 2,526,497; and 2,591,577. Addition ofphosphorothionyl disulfides as an antiwear, antioxidant, and EP additiveis disclosed in U.S. Pat. No. 3,770,854. Use of alkylthiocarbamoylcompounds (bis(dibutyl)thiocarbamoyl, for example) in combination with amolybdenum compound (oxymolybdenum diisopropylphosphorodithioatesulfide, for example) and a phosphorous ester (dibutyl hydrogenphosphite, for example) as antiwear additives in lubricants is disclosedin U.S. Pat. No. 4,501,678. U.S. Pat. No. 4,758,362 discloses use of acarbamate additive to provide improved antiwear and extreme pressureproperties. The use of thiocarbamate as an antiwear additive isdisclosed in U.S. Pat. No. 5,693,598. Thiocarbamate/molybdenum complexessuch as molysulfur alkyl dithiocarbamate trimer complex (R=C₈-C₁₈ alkyl)are also useful antiwear agents. Each of the aforementioned patents isincorporated by reference herein in its entirety.

[0051] Esters of glycerol may be used as antiwear agents. For example,mono-, di, and tri-oleates, mono-palmitates and mono-myristates may beused.

[0052] ZDDP is combined with other compositions that provide antiwearproperties. U.S. Pat. No. 5,034,141 discloses that a combination of athiodixanthogen compound (octylthiodixanthogen, for example) and a metalthiophosphate (ZDDP, for example) can improve antiwear properties. U.S.Pat. No. 5,034,142 discloses that use of a metal alkyoxyalkylxanthate(nickel ethoxyethylxanthate, for example) and a dixanthogen(diethoxyethyl dixanthogen, for example) in combination with ZDDPimproves antiwear properties. Each of the aforementioned patents isincorporated herein by reference in its entirety.

[0053] Preferred antiwear additives include phosphorus and sulfurcompounds such as zinc dithiophosphates and/or sulfur, nitrogen, boron,molybdenum phosphorodithioates, molybdenum dithiocarbamates and variousorgano-molybdenum derivatives including heterocyclics, for exampledimercaptothiadiazoles, mercaptobenzothiadiazoles, triazines, and thelike, alicyclics, amines, alcohols, esters, diols, triols, fatty amidesand the like can also be used. Such additives may be used in an amountof about 0.01 to 6 weight percent, preferably about 0.01 to 4 weightpercent.

[0054] Viscosity Index Improvers

[0055] Viscosity index improvers (also known as VI improvers, viscositymodifiers, and viscosity improvers) provide lubricants with high and lowtemperature operability. These additives impart shear stability atelevated temperatures and acceptable viscosity at low temperatures.

[0056] Suitable viscosity index improvers include high molecular weighthydrocarbons, polyesters and viscosity index improver dispersants thatfunction as both a viscosity index improver and a dispersant. Typicalmolecular weights of these polymers are between about 10,000 to1,000,000, more typically about 20,000 to 500,00, and even moretypically between about 50,000 and 200,000.

[0057] Examples of suitable viscosity index improvers are polymers andcopolymers of methacrylate, butadiene, olefins, or alkylated styrenes.Polyisobutylene is a commonly used viscosity index improver. Anothersuitable viscosity index improver is polymethacrylate (copolymers ofvarious chain length alkyl methacrylates, for example), someformulations of which also serve as pour point depressants. Othersuitable viscosity index improvers include copolymers of ethylene andpropylene, hydrogenated block copolymers of styrene and isoprene, andpolyacrylates (copolymers of various chain length acrylates, forexample). Specific examples include styrene-isoprene orstyrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

[0058] Viscosity index improvers may be used in an amount of about 0.01to 8 weight percent, preferably about 0.01 to 4 weight percent.

[0059] Antioxidants

[0060] Antioxidants retard the oxidative degradation of base oils duringservice. Such degradation may result in deposits on metal surfaces, thepresence of sludge, or a viscosity increase in the lubricant. Oneskilled in the art knows a wide variety of oxidation inhibitors that areuseful in lubricating oil compositions. See, Klamann in Lubricants andRelated Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197,for example, each of which is incorporated by reference herein in itsentirety.

[0061] Useful antioxidants include hindered phenols. These phenolicantioxidants may be ashless (metal-free) phenolic compounds or neutralor basic metal salts of certain phenolic compounds. Typical phenolicantioxidant compounds are the hindered phenolics which are the oneswhich contain a sterically hindered hydroxyl group, and these includethose derivatives of dihydroxy aryl compounds in which the hydroxylgroups are in the o- or p-position to each other. Typical phenolicantioxidants include the hindered phenols substituted with C₆+ alkylgroups and the alkylene coupled derivatives of these hindered phenols.Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol;2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol;2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecylphenol. Other useful hindered mono-phenolic antioxidants may include forexample hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.Bis-phenolic antioxidants may also be advantageously used in combinationwith the instant invention. Examples of ortho coupled phenols include:2,2′-bis(6-t-butyl-4-heptyl phenol); 2,2′-bis(6-t-butyl-4-octyl phenol);and 2,2′-bis(6-t-butyl-4-dodecyl phenol). Para coupled bis phenolsinclude for example 4,4′-bis(2,6-di-t-butyl phenol) and4,4′-methylene-bis(2,6-di-t-butyl phenol).

[0062] Non-phenolic oxidation inhibitors which may be used includearomatic amine antioxidants and these may be used either as such or incombination with phenolics. Typical examples of non-phenolicantioxidants include: alkylated and non-alkylated aromatic amines suchas aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic,aromatic or substituted aromatic group, R⁹ is an aromatic or asubstituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(X)R¹²where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is ahigher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1or 2. The aliphatic group R⁸ may contain from 1 to about 20 carbonatoms, and preferably contains from about 6 to 12 carbon atoms. Thealiphatic group is a saturated aliphatic group. Preferably, both R⁸ andR⁹ are aromatic or substituted aromatic groups, and the aromatic groupmay be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸and R⁹ may be joined together with other groups such as S.

[0063] Typical aromatic amines antioxidants have alkyl substituentgroups of at least about 6 carbon atoms. Examples of aliphatic groupsinclude hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphaticgroups will not contain more than about 14 carbon atoms. The generaltypes of amine antioxidants useful in the present compositions includediphenylamines, phenyl naphthyl-amines, phenothiazines, imidodibenzylsand diphenyl phenylene diamines. Mixtures of two or more aromatic aminesare also useful. Polymeric amine antioxidants can also be used.Particular examples of aromatic amine antioxidants useful in the presentinvention include: p,p′-dioctyldiphenylamine;t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; andp-octylphenyl-alpha-naphthylamine.

[0064] Sulfurized alkyl phenols and alkali or alkaline earth metal saltsthereof also are useful antioxidants. Low sulfur peroxide decomposersare useful as antioxidants.

[0065] Another class of antioxidant used in lubricating oil compositionsis oil-soluble copper compounds. Any oil-soluble suitable coppercompound may be blended into the lubricating oil. Examples of suitablecopper antioxidants include copper dihydrocarbyl thio ordithio-phosphates and copper salts of carboxylic acid (naturallyoccurring or synthetic). Other suitable copper salts include copperdithiocarbamates, sulphonates, phenates, and acetylacetonates. Basic,neutral, or acidic copper Cu(I) and or Cu(II) salts derived from alkenylsuccinic acids or anhydrides are know to be particularly useful.

[0066] Preferred antioxidants include hindered phenols, arylamines, lowsulfur peroxide decomposers and other related components. Theseantioxidants may be used individually by type or in combination with oneanother. Such additives may be used in an amount of about 0.01 to 5weight percent, preferably about 0.01 to 1.5 weight percent.

[0067] Detergents

[0068] Detergents are commonly used in lubricating compositions. Atypical detergent is an anionic material that contains a long chainoleophillic portion of the molecule and a smaller anionic or oleophobicportion of the molecule. The anionic portion of the detergent istypically derived from an organic acid such as a sulfur acid, carboxylicacid, phosphorous acid, phenol, or mixtures thereof. The counter ion istypically an alkaline earth or alkali metal.

[0069] Salts that contain a substantially stoichiometric amount of themetal are described as neutral salts and have a total base number (TBN,as measured by ASTM D2896) of from 0 to 80. Many compositions areoverbased, containing large amounts of a metal base that is achieved byreacting an excess of a metal compound (a metal hydroxide or oxide, forexample) with an acidic gas (such as carbon dioxide). Useful detergentscan be neutral, mildly overbased, or highly overbased.

[0070] It is desirable for at least some detergent to be overbased.Overbased detergents help neutralize acidic impurities produced by thecombustion process and become entrapped in the oil. Typically, theoverbased material has a ratio of metallic ion to anionic portion of thedetergent of about 1.05:1 to 50:1 on an equivalent basis. Morepreferably, the ratio is from about 4:1 to about 25:1. The resultingdetergent is an overbased detergent that will typically have a TBN ofabout 150 or higher, often about 250 to 450 or more. Preferably, theoverbasing cation is sodium, calcium, or magnesium. A mixture ofdetergents of differing TBN can be used in the present invention.

[0071] Preferred detergents include the alkali or alkaline earth metalsalts of sulfates, phenates, carboxylates, phosphates, and salicylates.

[0072] Sulfonates may be prepared from sulfonic acids that are typicallyobtained by sulfonation of alkyl substituted aromatic hydrocarbons.Hydrocarbon examples include those obtained by alkylating benzene,toluene, xylene, naphthalene, biphenyl and their halogenated derivatives(chlorobenzene, chlorotoluene, and chloronaphthalene, for example). Thealkylating agents typically have about 3 to 70 carbon atoms. The alkarylsulfonates typically contain about 9 to about 80 carbon or more carbonatoms, more typically from about 16 to 60 carbon atoms.

[0073] Klamann in Lubricants and Related Products, op cit discloses anumber of overbased metal salts of various sulfonic acids which areuseful as detergents and dispersants in lubricants. The book entitled“Lubricant Additives”, C. V. Smallheer and R. K. Smith, published by theLezius-Hiles Co. of Cleveland, Ohio (1967), similarly discloses a numberof overbased sulfonates which are useful as dispersants/detergents.

[0074] Alkaline earth phenates are another useful class of detergent.These detergents can be made by reacting alkaline earth metal hydroxideor oxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with analkyl phenol or sulfurized alkylphenol. Useful alkyl groups includestraight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀.Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol,nonylphenol, 1-ethyldecylphenol, and the like. It should be noted thatstarting alkylphenols may contain more than one alkyl substituent thatare each independently straight chain or branched. When a non-sulfurizedalkylphenol is used, the sulfurized product may be obtained by methodswell known in the art. These methods include heating a mixture ofalkylphenol and sulfurizing agent (including elemental sulfur, sulfurhalides such as sulfur dichloride, and the like) and then reacting thesulfurized phenol with an alkaline earth metal base.

[0075] Metal salts of carboxylic acids are also useful as detergents.These carboxylic acid detergents may be prepared by reacting a basicmetal compound with at least one carboxylic acid and removing free waterfrom the reaction product. These compounds may be overbased to producethe desired TBN level. Detergents made from salicylic acid are onepreferred class of detergents derived from carboxylic acids. Usefulsalicylates include long chain alkyl salicylates. One useful family ofcompositions is of the formula

[0076] where R is a hydrogen atom or an alkyl group having 1 to about 30carbon atoms, n is an integer from 1 to 4, and M is an alkaline earthmetal. Preferred R groups are alkyl chains of at least C₁₁, preferablyC₁₃ or greater. R may be optionally substituted with substituents thatdo not interfere with the detergent's function. M is preferably,calcium, magnesium, or barium. More preferably, M is calcium.

[0077] Hydrocarbyl-substituted salicylic acids may be prepared fromphenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791, which isincorporated herein by reference in its entirety, for additionalinformation on synthesis of these compounds. The metal salts of thehydrocarbyl-substituted salicylic acids may be prepared by doubledecomposition of a metal salt in a polar solvent such as water oralcohol.

[0078] Alkaline earth metal phosphates are also used as detergents.

[0079] Detergents may be simple detergents or what is known as hybrid orcomplex detergents. The latter detergents can provide the properties oftwo detergents without the need to blend separate materials. See U.S.Pat. No. 6,034,039 for example. Preferred detergents include calciumphenates, calcium sulfonates, calcium salicylates, magnesium phenates,magnesium sulfonates, magnesium salicylates and other related components(including borated detergents). Typically, the total detergentconcentration is about 0.01 to about 6.0 weight percent, preferably,about 0.1 to 0.4 weight percent.

[0080] Dispersant

[0081] During engine operation, oil insoluble oxidation byproducts areproduced. Dispersants help keep these byproducts in solution, thusdiminishing their deposit on metal surfaces. Dispersants may be ashlessor ash-forming in nature. Preferably, the dispersant is ashless. Socalled ashless dispersants are organic materials that form substantiallyno ash upon combustion. For example, non-metal-containing or boratedmetal-free dispersants are considered ashless. In contrast,metal-containing detergents discussed above form ash upon combustion.

[0082] Suitable dispersants typically contain a polar group attached toa relatively high molecular weight hydrocarbon chain. The polar grouptypically contains at least one element of nitrogen, oxygen, orphosphorous. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

[0083] Chemically, many dispersants may be characterized as phenates,sulfonates, sulfurized phenates, salicylates, naphthenates, stearates,carbamates, thiocarbamates, phosphorus derivatives. A particularlyuseful class of dispersants are the alkenylsuccinic derivatives,typically produced by the reaction of a long chain substituted alkenylsuccinic compound, usually a substituted succinic anhydride, with apolyhydroxy or polyamino compound. The long chain group constituting theoleophilic portion of the molecule which confers solubility in the oil,is normally a polyisobutylene group. Many examples of this type ofdispersant are well known commercially and in the literature. ExemplaryU.S. patents describing such dispersants are U.S. Pat. Nos. 3,172,892;3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607;3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types ofdispersant are described in U.S. Pat. Nos. 3,036,003; 3,200,107;3,254,025; 3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347;3,697,574; 3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658;3,449,250; 3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082;5,705,458. A further description of dispersants may be found, forexample, in European Patent Application No. 471 071, to which referenceis made for this purpose. Each of the aforementioned patents isincorporated herein in its entirety by reference.

[0084] Hydrocarbyl-substituted succinic acid compounds are populardispersants. In particular, succinimide, succinate esters, or succinateester amides prepared by the reaction of a hydrocarbon-substitutedsuccinic acid compound preferably having at least 50 carbon atoms in thehydrocarbon substituent, with at least one equivalent of an alkyleneamine are particularly useful.

[0085] Succinimides are formed by the condensation reaction betweenalkenyl succinic anhydrides and amines. Molar ratios can vary dependingon the polyamine. For example, the molar ratio of alkenyl succinicanhydride to TEPA can vary from about 1:1 to about 5:1. Representativeexamples are shown in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666;3,272,746; 3,322,670; and 3,652,616, 3,948,800; and Canada Pat. No.1,094,044, which are incorporated herein in their entirety by reference.

[0086] Succinate esters are formed by the condensation reaction betweenalkenyl succinic anhydrides and alcohols or polyols. Molar ratios canvary depending on the alcohol or polyol used. For example, thecondensation product of an alkenyl succinic anhydride andpentaerythritol is a useful dispersant.

[0087] Succinate ester amides are formed by condensation reactionbetween alkenyl succinic anhydrides and alkanol amines. For example,suitable alkanol amines include ethoxylated polyalkylpolyamines,propoxylated polyalkylpolyamines and polyalkenylpolyamines such aspolyethylene polyamines. One example is propoxylatedhexamethylenediamine. Representative examples are shown in U.S. Pat. No.4,426,305, incorporated herein by reference.

[0088] The molecular weight of the alkenyl succinic anhydrides used inthe preceding paragraphs will typically range between 800 and 2,500. Theabove products can be post-reacted with various reagents such as sulfur,oxygen, formaldehyde, carboxylic acids such as oleic acid, and boroncompounds such as borate esters or highly borated dispersants. Thedispersants can be borated with from about 0.1 to about 5 moles of boronper mole of dispersant reaction product.

[0089] Mannich base dispersants are made from the reaction ofalkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,551,which is incorporated herein by reference. Process aids and catalysts,such as oleic acid and sulfonic acids, can also be part of the reactionmixture. Molecular weights of the alkylphenols range from 800 to 2,500.Representative examples are shown in U.S. Pat. Nos. 3,697,574;3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039,which are incorporated herein in their entirety by reference.

[0090] Typical high molecular weight aliphatic acid modified Mannichcondensation products useful in this invention can be prepared from highmolecular weight alkyl-substituted hydroxyaromatics or HN(R)₂group-containing reactants.

[0091] Examples of high molecular weight alkyl-substitutedhydroxyaromatic compounds are polypropylphenol, polybutylphenol, andother polyalkylphenols. These polyalkylphenols can be obtained by thealkylation, in the presence of an alkylating catalyst, such as BF₃, ofphenol with high molecular weight polypropylene, polybutylene, and otherpolyalkylene compounds to give alkyl substituents on the benzene ring ofphenol having an average 600-100,000 molecular weight.

[0092] Examples of HN(R)₂ group-containing reactants are alkylenepolyamines, principally polyethylene polyamines. Other representativeorganic compounds containing at least one HN(R)₂ group suitable for usein the preparation of Mannich condensation products are well known andinclude the mono- and di-amino alkanes and their substituted analogs,e.g., ethylamine and diethanol amine; aromatic diamines, e.g., phenylenediamine, diamino naphthalenes; heterocyclic amines, e.g., morpholine,pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine; melamineand their substituted analogs.

[0093] Examples of alkylene polyamide reactants include ethylenediamine,diethylene triamine, triethylene tetraamine, tetraethylene pentaamine,pentaethylene hexamine, hexaethylene heptaamine, heptaethyleneoctaamine, octaethylene nonaamine, nonaethylene decamine, anddecaethylene undecamine and mixture of such amines having nitrogencontents corresponding to the alkylene polyamines, in the formulaH₂N-(Z-NH—)_(n)H, mentioned before, Z is a divalent ethylene and n is 1to 10 of the foregoing formula. Corresponding propylene polyamines suchas propylene diamine and di-, tri-, tetra-, pentapropylene tri-, tetra-,penta- and hexaamines are also suitable reactants. The alkylenepolyamines are usually obtained by the reaction of ammonia and dihaloalkanes, such as dichloro alkanes. Thus the alkylene polyamines obtainedfrom the reaction of 2 to 11 moles of ammonia with 1 to 10 moles ofdichloro alkanes having 2 to 6 carbon atoms and the chlorines ondifferent carbons are suitable alkylene polyamine reactants.

[0094] Aldehyde reactants useful in the preparation of the highmolecular products useful in this invention include the aliphaticaldehydes such as formaldehyde (also as paraformaldehyde and formalin),acetaldehyde and aldol (b-hydroxybutyraldehyde). Formaldehyde or aformaldehyde-yielding reactant is preferred.

[0095] Hydrocarbyl substituted amine ashless dispersant additives arewell known to one skilled in the art; see, for example, U.S. Pat. Nos.3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197,which are incorporated herein in their entirety by reference.

[0096] Preferred dispersants include borated and non-boratedsuccinimides, including those derivatives from mono-succinimides,bis-succinimides, and/or mixtures of mono- and bis-succinimides, whereinthe hydrocarbyl succinimide is derived from a hydrocarbylene group suchas polyisobutylene having a Mn of from about 500 to about 5000,preferably from about 1000 to 3000, more preferably from about 1000 to2000, and even more preferably from about 1000 to 1600 or a mixture ofsuch hydrocarbylene groups. Other preferred dispersants include succinicacid-esters and amides, alkylphenol-polyamine coupled Mannich adducts,their capped derivatives, and other related components. Such additivesmay be used in an amount of about 0.1 to 20 weight percent, preferablyabout 0.1 to 8 weight percent.

[0097] Pour Point Depressants

[0098] Conventional pour point depressants (also known as lube oil flowimprovers) may be added to the compositions of the present invention ifdesired. These pour point depressant may be added to lubricatingcompositions of the present invention to lower the minimum temperatureat which the fluid will flow or can be poured. Examples of suitable pourpoint depressants include polymethacrylates, polyacrylates,polyarylamides, condensation products of haloparaffin waxes and aromaticcompounds, vinyl carboxylate polymers, and terpolymers ofdialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers.U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479;2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pourpoint depressants and/or the preparation thereof. Each of thesereferences is incorporated herein in its entirety. Such additives may beused in an amount of about 0.01 to 5 weight percent, preferably about0.01 to 1.5 weight percent.

[0099] Corrosion Inhibitors

[0100] Corrosion inhibitors are used to reduce the degradation ofmetallic parts that are in contact with the lubricating oil composition.Suitable corrosion inhibitors include thiadizoles. See, for example,U.S. Pat. Nos. 2,719, 125; 2,719,126; and 3,087,932, which areincorporated herein by reference in their entirety. Such additives maybe used in an amount of about 0.01 to 5 weight percent, preferably about0.01 to 1.5 weight percent.

[0101] Seal Compatibility Additives

[0102] Seal compatibility agents help to swell elastomeric seals bycausing a chemical reaction in the fluid or physical change in theelastomer. Suitable seal compatibility agents for lubricating oilsinclude organic phosphates, aromatic esters, aromatic hydrocarbons,esters (butylbenzyl phthalate, for example), and polybutenyl succinicanhydride. Such additives may be used in an amount of about 0.01 to 3weight percent, preferably about 0.01 to 2 weight percent.

[0103] Anti-Foam Agents

[0104] Anti-foam agents may advantageously be added to lubricantcompositions. These agents retard the formation of stable foams.Silicones and organic polymers are typical anti-foam agents. Forexample, polysiloxanes, such as silicon oil or polydimethyl siloxane,provide antifoam properties. Anti-foam agents are commercially availableand may be used in conventional minor amounts along with other additivessuch as demulsifiers; usually the amount of these additives combined isless than 1 percent and often less than 0.1 percent.

[0105] Inhibitors and Antirust Additives

[0106] Antirust additives (or corrosion inhibitors) are additives thatprotect lubricated metal surfaces against chemical attack by water orother contaminants. A wide variety of these are commercially available;they are referred to in Klamann in Lubricants and Related Products, opcite.

[0107] One type of antirust additive is a polar compound that wets themetal surface preferentially, protecting it with a film of oil. Anothertype of antirust additive absorbs water by incorporating it in awater-in-oil emulsion so that only the oil touches the metal surface.Yet another type of antirust additive chemically adheres to the metal toproduce a non-reactive surface. Examples of suitable additives includezinc dithiophosphates, metal phenolates, basic metal sulfonates, fattyacids and amines. Such additives may be used in an amount of about 0.01to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

[0108] Friction Modifiers

[0109] A friction modifier is any material or materials that can alterthe coefficient of friction of any lubricant or fluid containing suchmaterial(s). Friction modifiers, also known as friction reducers, orlubricity agents or oiliness agents, and other such agents that changethe coefficient of friction of lubricant base oils, formulated lubricantcompositions, or functional fluids, may be effectively used incombination with the base oils or lubricant compositions of the presentinvention if desired. Friction modifiers that lower the coefficient offriction are particularly advantageous in combination with the base oilsand lube compositions of this invention. Friction modifiers may includemetal-containing compounds or materials as well as ashless compounds ormaterials, or mixtures thereof Metal-containing friction modifiers mayinclude metal salts or metal-ligand complexes where the metals mayinclude alkali, alkaline earth, or transition group metals. Suchmetal-containing friction modifiers may also have low-ashcharacteristics. Transition metals may include Mo, Sb, Sn, Fe, Cu, Zn,and others. Ligands may include hydrocarbyl derivative of alcohols,polyols, glycerols, partial ester glycerols, thiols, carboxylates,carbamates, thiocarbamates, dithiocarbamates, phosphates,thiophosphates, dithiophosphates, amides, imides, amines, thiazoles,thiadiazoles, dithiazoles, diazoles, triazoles, and other polarmolecular functional groups containing effective amounts of O, N, S, orP, individually or in combination. In particular, Mo-containingcompounds can be particularly effective such as for exampleMo-dithiocarbamates, Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines,Mo (Am), Mo-alcoholates, Mo-alcohol-amides, etc.

[0110] Ashless friction modifiers may have also include lubricantmaterials that contain effective amounts of polar groups, for examplehydroxyl-containing hydrocaryl base oils, glycerides, partialglycerides, glyceride derivatives, and the like. Polar groups infriction modifiers may include hyrdocarbyl groups containing effectiveamounts of O, N, S, or P, individually or in combination. Other frictionmodifiers that may be particularly effective include, for example, salts(both ash-containing and ashless derivatives) of fatty acids, fattyalcohols, fatty amides, fatty esters, hydroxyl-containing carboxylates,and comparable synthetic long-chain hydrocarbyl acids, alcohols, amides,esters, hydroxy carboxylates, and the like. In some instances fattyorganic acids, fatty amines, and sulfurized fatty acids may be used assuitable friction modifiers.

[0111] Useful concentrations of friction modifiers may range from about0.01 wt % to 10-15 wt % or more, often with a preferred range of about0.1 wt % to 5 wt %. Concentrations of molybdenum containing materialsare often described in terms of Mo metal concentration. Advantageousconcentrations of Mo may range from about 10 ppm to 3000 ppm or more,and often with a preferred range of about 20-2000 ppm, and in someinstances a more preferred range of about 30-1000 ppm. Frictionmodifiers of all types may be used alone or in mixtures with thematerials of this invention. Often mixtures of two or more frictionmodifiers, or mixtures of friction modifiers(s) with alternate surfaceactive material(s), are also desirable.

[0112] Typical Additive Amounts

[0113] When lubricating oil compositions contain one or more of theadditives discussed above, the additive(s) are blended into thecomposition in an amount sufficient for it to perform its intendedfunction. Typical amounts of such additives useful in the presentinvention are shown in the table below.

[0114] Note that many of the additives are shipped from the manufacturerand used with a certain amount of base oil solvent in the formulation.Accordingly, the weight amounts in the table below, as well as otheramounts mentioned in this patent, are directed to the amount of activeingredient (that is the non-solvent or non-diluent portion of theingredient). The weight percents indicated below are based on the totalweight of the lubricating oil composition. TABLE 1 Typical Amounts ofVarious Lubricant Oil Components Approximate Weight Approximate WeightCompound Percent (Useful) Percent (Preferred) Detergent  0.01-6  0.01-4Dispersant  0.1-20  0.14-8 Friction  0.01-5  0.01-1.5 Reducer ViscosityIndex  0.0-40  0.01-30, Improver more preferably 0.01-15 Antioxidant 0.01-5  0.01-1.5 Corrosion  0.01-5  0.01-1.5 Inhibitor Anti-wear 0.01-6  0.01-4 Additive Pour Point  0.0-5  0.01-1.5 DepressantAnti-foam Agent 0.001-3 0.001-0.15 Base Oil Balance Balance

[0115] Experimental

[0116] Unless otherwise specified, kinematic viscosity at 40° C. or 100°C. is determined according to ASTM test method D 445, viscosity index isdetermined by ASTM test method D 2270, pour point is determined by ASTMtest method D 97, and TBN by ASTM test method number D 2896.

[0117] The hydrocarbyl aromatic in the following examples is alkylatednaphthalene (primarily mono-alkylated) having a kinematic viscosity ofapproximately 4.6 cSt at 100° C. The primarily mono-alkylatednaphthalene is prepared by the alkylation of naphthalene with an olefinprimarily comprised of 1-hexadecene.

[0118] In the Examples, the components listed below are used in thelubricant compositions: TABLE 2 Typical Base Stock Properties Hydro-Hydro- PE TMP GpIII treated treated Hydrocarbyl PAO PAO derived derived4 A B Aromatic 4 6 ester ester D 445 Kinematic 15.6 36.2 22.65 29.3 1831 29.8 18.4 Viscosity at 40 C., cSt D 445 Kinematic 3.8 6 4.55 4.7 4 65.94 4.2 Viscosity at 100 C., cSt D 2272 Viscosity 138 114 116 75 120138 149 136 Index D 1500 ASTM 0 0 L5.0 1.0 0 0 Color D 2007 Saturates,na 96 97 na 100 100 0 0 wt % D 2662 Sulfur, ppm 0 40 60 150 0 0 0 0 APIGroup III II II V IV IV V V

[0119] All examples shown herein illustrate the instant invention but donot limit the composition for this invention.

[0120] A series of industry-sanctioned Sequence VIB fuel economy enginetests (ASTM Research Report D02-1469) were performed to determine theeffect of compositional changes upon fuel economy of the testlubricants. The fuel economy improvement (FEI) limits for the variousSAE viscosity grades is given in ASTM D 4485. Referring to Table 3,Comparative Example 3.1 serves as the reference engine test formulationand establishes the base-line FEI value used in comparison to that ofthe inventive Examples. The percent difference (positive or negative)for FEI between Comparative Example 3.1 and the standard D 4485 limit isfirst calculated. Similarly, the percent differences (positive ornegative) for FEI between the various candidate oils and the standardD4485 limit is then calculated. The percent advantage of the candidateFEI value over the Comparative Example 3.1 FEI value is then calculated.The percent advantage results for each of the candidate oils aresummarized in Table 3 below. TABLE 3 Results from fuel economy tests fortest oils containing pentaerythritol esters. Examples 3.1 3.2 3.3 3.43.5 3.6 SAE Oil Viscosity 5W-30 10W-30 10W-30 10W-30 5W-30 5W-30Performance Additives to 16.1 15.8 15.8 15.7 16.7 16.0 deliverapproximately 2% active borated succinimide type dispersant based ontotal composition Hydrotreated Base Oil A 0 0 0 20.0 0 0 HydrotreatedBase Oil B 0 0 40.0 20.0 0 0 GpIII 4 0 0 0 0 0 0 4 cS PAO 40.9 45.5 27.330.7 63.3 69.8 6 cS PAO 25.0 19.0 0 0 0 0 Pentaerythritol derived ester0 15.0 12.0 9.4 11.0 8.6 Trimethylolpropane derived 2.0 0 0 0 2.0 0ester Hydrocarbyl Aromatic 16.0 4.7 4.9 4.2 7.0 5.6 Performance Phase IFEI % 1.1 1.3 1.2 1.0 1.5 1.6 Overall Enhancement relative Base 78.066.0 44.0 25.0 31.0 to SAE viscosity grade

[0121] It is unexpectedly found that the addition of from about 8-9 toabout 15% of the above-described pentaerythritol ester (PE ester)provided significant and surprising fuel economy enhancements. Theadmixture of 9.4% of such PE ester to a SAE 10W-30 automotive engine oilexhibited a surprising 44% fuel economy enhancement. The admixture of12% of such PE ester to a SAE 10W-30 automotive engine oil exhibited asurprising 65% fuel economy enhancement. The admixture of 15% of such PEester to a SAE 10W-30 automotive engine oil exhibited a surprising 77%fuel economy enhancement. It is found that increasing concentrations ofsuch PE ester resulted in greater fuel economy enhancements. Each ofthese test oils contained a hydrocarbyl aromatic base oil, and it isbelieved that the presence of such hydrocarbyl aromatic may havecontributed to the favorable results obtained.

[0122] It is unexpectedly found that the addition of about 8% or greaterof the above-described pentaerythritol ester (PE ester) optionallycoupled with the addition of 2% trimethylolpropane ester provided evenmore significant and more surprising fuel economy enhancements of atleast 25% in Sequence VIB engine testing. These test oils containhydrocarbyl aromatics, and it is believed that the presence of suchhydrocarbyl aromatics may have contributed to the favorable resultsobtained.

[0123] As shown by Examples 3.2, 3.3, and 3.4 of Table 3, fuel economyenhancements of up to 78% are found with such combinations. The benefitmay reach a maximum with the use of about 0% to about 20% hydrocarbylaromatic, about 20% to about 60% Group II type paraffinic base stock andabout 0.5% to about 5% by weight, of the neat borated polyisobutenylsuccinimide ashless dispersant (0.33 wt % to 3.3 wt % active ingredient)where the polyisobutenyl mono and bis succinimide is made by thereaction of polyisobutenyl succinic anhydride with an approximate M_(n)of −1300 for the PIB group with amines. Preferred amounts may be fromabout 4% to about 15% hydrocarbyl aromatic, about 30% to about 50% GroupII type paraffinic base stocks and about 1% to about 4% boratedpolyisobutenyl succinimide ashless dispersant as received by weight thatcorrespond with HFRR testing of dispersants in FIG. 1. The neat boratedpolyisobutenyl succinimide ashless dispersant is approximatelytwo-thirds active ingredient and provides about 2% active ingredientwhen added to the oil blends.

[0124] One of ordinary skill in the art would easily note that thesefindings may be extended to any paraffinic base stock. The inventorsnote that this discovery may also employ Group III base stocks, andpreferably Gas-to-Liquids or Fischer-Tropsch base stocks. Thus, as annon-limiting illustrative sample, the inventors also note that a mixtureof about 70 wt % Group III base stock, about 8 to 9 wt % Pentaerythritolderived ester and about 5 to 6 wt % Hydrocarbyl Aromatics, with theremainder being a Performance Additive package will also achieve thesame surprising Fuel Economy increases.

[0125] A series of industry-sanctioned Sequence VIB fuel economy enginetests is performed to determine the effect of compositional changes uponfuel economy of the test lubricants. Referring to Table 4, ComparativeExample 4.1 is used as the reference engine test formulation toestablish the base-line FEI value used in subsequent calculations asdescribed above. TABLE 4 Results from fuel economy tests for GroupII/Group III-type paraffinic oil blends and hydrocarbyl aromaticsExamples 4.1 4.2 4.3 4.4 SAE Oil Viscosity 5W-30 5W-30 5W-30 5W-30Performance Additives to deliver 15.9 16.1 15.7 15.7 approximately 2%active borated succinimide type dispersant based on total compositionHydrotreated Base Oil B 37.5 0 44.0 44.0 GpIII 4 0 0 0 0 4 cS PAO 37.640.9 32.8 33.2 6 cS PAO 0 25.0 0 0 Trimethylolpropane derived ester 2.02.0 2.0 2.0 Hydrocarbyl Aromatic 7.0 16.0 5.5 5.1 Performance Phase IFEI % 1.1 1.1 1.5 1.6 Overall Enhancement relative to Base Base 26 30SAE viscosity grade

[0126] It is surprisingly found that when relatively high concentrationsof Group II/Group III type paraffinic base stock is included in lubecompositions in the presence of both hydrocarbyl aromatic and polyolesters, such as those derived from trimethylolpropane, significant FEIenhancements are unexpectedly found in Sequence VIB engine testing. Withthe use of approximately 44% such paraffinic base oil, approximately 2%trimethylol-propane ester, and approximately 5% alkylated naphthalene asthe hydrocarbyl aromatic, a fuel economy enhancement of 30% is observed.With the use of approximately 44% such paraffinic base oils,approximately 2% trimethylol-propane ester, and approximately 5.5%alkylated naphthalene as the hydrocarbyl aromatic, an equally surprisingfuel economy enhancement of 26% is found. The benefit may reach amaximum with the use of about 3% to 30% hydrocarbyl aromatic, about 40%to about 90% paraffinic base oil and about 1% to about 20%trimethylolpropane ester with preferred amounts being about 4% to about20% hydrocarbyl aromatic, about 40% or greater of paraffinic base oilsand about 2% to about 10% trimethylolpropane ester. These engine testsclearly demonstrate the advantages of such fuel economy improvingformulations.

[0127] We believe that the fuel economy benefit can be further enhancedwhen the above Group II/III type paraffinic stocks are used in thepresence of about 1% to about 10% or more of any traditional polyolester and/or hydrocarbyl aromatic such as alkyl naphthalene and/or otherco-base oils in the finished formulated lubricant.

[0128] One of ordinary skill in the art would easily note that thesefindings may be extended to any paraffinic base stock. The inventorsnote that this discovery may also employ Group III base stocks, andpreferably Gas-to-Liquids or Fischer-Tropsch base stocks. Thus, as annon-limiting illustrative sample, the inventors also note that a mixtureof about 40 wt % Group III base stock, about 30 to 35% PAO, about 2 wt %Trimethylolpropane and about 4 to 6 wt % Hydrocarbyl Aromatics, with theremainder being a Performance Additive package will also achieve thesame surprising Fuel Economy increases.

[0129] Certain amorphous olefin copolymers are found to provideunexpected and significant fuel economy improving (friction reducing)benefits when formulated into lubricants, especially those containingsignificant amounts of Group II or Group III base oils having viscosityindices of about 110 to about 150 or greater. A series ofindustry-sanctioned Sequence VIB fuel economy engine tests is performedto determine the effect of compositional changes upon fuel economy ofthe test lubricants. Comparative Example 5.1 is used as the referenceengine test formulation to establish the base-line FEI value used insubsequent calculations as described above.

[0130] It is surprisingly found that the addition of 5% of an amorphousolefin copolymer to a formulated oil blended with mixed Group II/GroupIII and polyalpha olefin base stocks derived from decene-type olefins,that the fuel economy enhancement in Sequence VIB engine testing is asurprising 26% to 38% enhancement. These results clearly show theunexpected fuel economy improving benefits of such formulationscomprising amorphous olefin copolymers at about 1% to about 20% whereabout 2% to about 15% is preferred and about 3% to about 10% is mostpreferred. TABLE 5 Results from fuel economy tests for amorphous OCPtype oil blends and hydrocarbyl aromatics Examples 5.1 5.2 5.3 SAE OilViscosity 5W-30 5W-30 5W-30 Performance Additives to deliverapproximately 2% active 16.1 15.4 15.3 borated succinimide typedispersant based on total composition Amorphous OCP 0 5.0 5.0Hydrotreated Base Oil B 0 31.0 31.0 GpIII 4 0 0 0 4 cS PAO 40.9 39.639.7 6 cS PAO 25.0 0 0 Trimethylolpropane derived ester 2.0 2.0 2.0Hydrocarbyl Aromatic 16.0 7.0 7.0 Performance Phase I FEI % 1.1 1.7 1.5Overall Enhancement relative to SAE viscosity grade Base 38 26

[0131] The inventors have found that the fuel economy benefit can befurther enhanced when the above amorphous olefin copolymer is used inthe presence of about 1% to about 10% or more of any traditional polyolester and/or hydrocarbyl aromatic such as alkyl naphthalene and/or otherco-base oils in the finished formulated lubricant.

[0132] One of ordinary skill in the art would easily note that thesefindings may be extended to any paraffinic base stock. The inventorsnote that this discovery may also employ Group III base stocks, andpreferably Gas-to-Liquids or Fischer-Tropsch base stocks. Thus, as annon-limiting illustrative sample, the inventors also note that a mixtureof about 30 wt %o Group III base stock, about 40 wt % PAO, about 2 wt %Trimethylolpropane and about 4 to 10 wt % Hydrocarbyl Aromatics, withthe remainder being a Performance Additive package will also achieve thesame surprising Fuel Economy increases.

[0133] Sequence VIB engine testing shows that significant fuel economyenhancements can be attained with the use of moderate concentrations ofhydrocarbyl aromatics, preferably in the presence of at least a minorconcentration of Group II or Group III, or hydrocracked and/orhydrotreated base stocks, including wax isomerate base oils. Thepresence of certain ashless dispersants also can significantlycontribute to the fuel economy enhancements observed. A series ofindustry-sanctioned Sequence VIB fuel economy engine tests is performedto determine the effect of compositional changes upon fuel economy ofthe test lubricants. Comparative Example 6.1 is used as the referenceengine test formulation to establish the base-line FEI value used insubsequent calculations as described above.

[0134] It is surprisingly found that fuel economy enhancements can beattained with the use of certain paraffinic base stocks in the presenceof moderate concentrations of hydrocarbyl aromatics, preferably in thepresence of certain borated polyisobutenyl succinimide ashlessdispersants. As shown by Examples 6.2, 6.3 and 6.4 of Table 6, fueleconomy enhancements of up to 77% are found with such combinations. Thebenefit may reach a maximum with the use of about 0% to about 20%hydrocarbyl aromatic, about 20% to about 60% Group II type paraffinicbase stocks and about 0.5% to about 5% by weight, as received, of aborated polyisobutenyl succinimide ashless dispersant. Preferred amountsmay be from about 4% to about 15% hydrocarbyl aromatic, about 30% toabout 50% Group II type paraffinic base stocks and about 1% to about 4%borated polyisobutenyl succinimide ashless dispersant as received byweight that correspond with HFRR testing of dispersants in FIG. 1. TheSequence VIB fuel economy engine test results clearly show theunexpected advantages obtainable by using the components of thisinvention. TABLE 6 Results from fuel economy testshydrocracked/hydrotreated stocks used with synergistic amounts ofhydrocarbyl aromatics as fuel economy improving compositions. Examples6.1 6.2 6.3 6.4 SAE Oil Viscosity 5W-30 10W-30 10W-30 10W-30 PerformanceAdditive Package 15.9 15.5 15.6 15.5 containing 3% borated succinimidetype dispersant Hydrotreated Base Oil A 0 0 35.0 35.0 Hydrotreated BaseOil B 37.5 0 5.0 0 GpIII 4 0 0 0 0 4 cS PAO 37.6 4.0 22.4 7.5 6 cS PAO 023.5 0 25.0 8 cS PAO 0 15.0 0 0 Trimethylolpropane derived ester 2.0 2.02.0 2.0 Hydrocarbyl Aromatic 7.0 40.0 20.0 15.0 Performance Phase I FEI% 1.1 1.0 1.3 0.9 Overall Enhancement relative to Base 78 66 44 SAEviscosity grade

[0135] One of ordinary skill in the art would easily note that thesefindings may be extended to any paraffinic base stock. The inventorsnote that this discovery may also employ Group III base stocks, andpreferably Gas-to-Liquids or Fischer-Tropsch base stocks. Thus, as annon-limiting illustrative sample, the inventors also note that a mixtureof about 30 wt % Group III base stock, about 30 to 40% PAO, about 2 wt %Trimethylolpropane and about 5 to 40 wt % Hydrocarbyl Aromatics, withthe remainder being a Performance Additive package will also achieve thesame surprising Fuel Economy increases.

[0136] All U.S. patents, non-U.S. patents and applications, andnon-patent references cited in this application are hereby incorporatedin their entirety by reference.

What is claimed is:
 1. A lubricating composition comprising a mixture ofabout 3 wt % to about 30 wt % pentaerythritol esters in a base stockwherein said lubricating composition contains more than about 18 wt %saturates and wherein the percentages are based upon the totallubricating composition.
 2. A lubricating composition as in claim 1wherein the composition contains at least 20 wt % of a base stock havingat least 90% saturates wherein the percentages are based upon the totallubricating composition.
 3. A lubricating composition as in claim 1wherein said base stock is a GTL base stock.
 4. A lubricatingcomposition as in claim 1 including at least one triol ester.
 5. Alubricating composition as in claim 4 wherein said base stock includesat least 90% saturates.
 6. A lubricating composition as in any one ofthe claims 4 or 5 wherein said triol esters are provided at about atleast 2 wt %.
 7. A lubricating composition as in claim 6 wherein saidbase stock is a GTL base stock.
 8. A lubricating composition as in claim1 including a borated hydrocarbyl-substituted succinimide wherein thehydrocarbyl group has a Mn from about 1000 to about
 5000. 9. Alubricating composition as in claim 8 wherein said boratedpolyisobutenyl succinimide is provided at about at least 0.3 wt % activeto about 3.3 wt % active.
 10. A lubricating composition as in claim 9where said borated isobutenyl succinimide comprises both mono and bissuccinimides.